U.S. patent application number 17/601622 was filed with the patent office on 2022-03-31 for method for producing three-dimensional shaped product, and three-dimensional shaped product obtained by the method.
The applicant listed for this patent is c/o Matsuura Machinery Corporation. Invention is credited to Koichi Amaya, Ryuzo Tanaka, Midorikawa Tetsushi, Seiichi Tomita.
Application Number | 20220097297 17/601622 |
Document ID | / |
Family ID | |
Filed Date | 2022-03-31 |
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United States Patent
Application |
20220097297 |
Kind Code |
A1 |
Amaya; Koichi ; et
al. |
March 31, 2022 |
Method for Producing Three-Dimensional Shaped Product, and
Three-Dimensional Shaped Product Obtained by the Method
Abstract
A method for producing a three-dimensional shaped product based
on repetition of a step of molding of a powder layer 3 and
sintering with a laser beam or an electron beam, wherein in a
lattice region 1, a sintered layer 41 is molded by scanning the
beam having a predetermined spot diameter several times in one side
direction at a predetermined interval, after which a sintered layer
42 is again molded by the same scanning in the other side direction
which crosses the one side direction, and in an outer frame region
2, a continuous sintered layer 43 is molded by scanning the beam
having the predetermined spot diameter over the entire lattice
region 1 that is surrounded by an inner line and an outer line, and
is also achieved by a three-dimensional shaped product obtained by
the method.
Inventors: |
Amaya; Koichi; (Fukui City,
Fukui, JP) ; Tetsushi; Midorikawa; (Fukui City,
Fukui, JP) ; Tomita; Seiichi; (Fukui City, Fukui,
JP) ; Tanaka; Ryuzo; (Fukui City, Fukui, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
c/o Matsuura Machinery Corporation |
Fukui City, Fukui |
|
JP |
|
|
Appl. No.: |
17/601622 |
Filed: |
April 30, 2021 |
PCT Filed: |
April 30, 2021 |
PCT NO: |
PCT/JP2021/017264 |
371 Date: |
October 5, 2021 |
International
Class: |
B29C 64/153 20060101
B29C064/153; B29C 64/268 20060101 B29C064/268; B29C 64/205 20060101
B29C064/205 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 1, 2020 |
JP |
2020-095202 |
Claims
1. A method for producing a three-dimensional shaped product
comprising the steps of: establishing layering based on sequential
repetition of steps of molding a powder layer by: dispersion of
powder, sliding a squeegee over the dispersed powder and sintering
the powder layer using a laser beam or an electron beam, targeting
the sintering for each powder layer to: an outer frame region which
is connected to a gas-permeable lattice region and outsides of the
region and is disposed around the entire periphery of the region,
and molding, for each of the powder layers targeted for the lattice
region, a sintered layer along one side direction by parallel
scanning of the laser beam or the electron beam having a
predetermined spot diameter several times in the one side direction
at a predetermined interval with mutually facing outer frame
regions bonded, thereafter molding a sintered layer in another side
direction again by parallel scanning of the laser beam or the
electron beam having the predetermined spot diameter several times
at the predetermined interval with mutually facing outer frame
regions bonded, in the another side direction that crosses with the
one side direction within each of the same powder layers, such
that: the sintered layer along the one side direction and the
sintered layer along the another side direction are crossing, and
the sintered layer along one side and the sintered layer along
another side are bonded in a superimposed state in a crossed
region, carrying out sintering on only one side or only on the
another side in a non-crossed region, molding, while in the outer
frame regions, a continuous sintered layer by scanning the laser
beam or the electron beam having the predetermined spot diameter
over the entire periphery that is surrounded by an inner line and
an outer line.
2. The method for producing a three-dimensional shaped product
according to claim 1, wherein for the shape of the outer frame
region, the inner line and the outer line have identical center
locations, and further comprising the step of employing either a
regular polygonal shape or a curved shape in a mutually similar
relationship.
3. The method for producing a three-dimensional shaped product
according to claim 1, further comprising the steps of: separating
the outer frame regions by a predetermined width and which are
divided by parallel lines selected in specific directions, and
scanning the laser beam or the electron beam in a direction
perpendicular to a parallel direction in an early stage, a later
stage, or an intermediate stage of molding for the sintered layers
in the lattice region.
4. The method for producing a three-dimensional shaped product
according to claim 3, wherein the parallel lines are in the
direction of a specific side of a regular polygonal shape.
5. The method for producing a three-dimensional shaped product
according to claim 3, wherein the parallel lines are in a direction
forming a maximum distance in the region surrounded by the inner
line and the outer line forming a regular polygonal shape or a
curved shape, for a predetermined width.
6. The method for producing a three-dimensional shaped product
according to claim 1, further comprising the step of scanning, at
an early stage, a later stage or an intermediate stage of molding
for the sintered layer in the lattice region, the laser beam or the
electron beam along a trajectory where the inner line and the outer
line forming a regular polygonal shape or a curved shape are in a
similar relationship.
7. The method for producing a three-dimensional shaped product
according to claim 1, further comprising the steps of: selecting a
spot diameter that is larger than a spot diameter in the lattice
region for the laser beam or the electron beam scanning the outer
frame region, and setting a power density such that power of the
laser beam or the electron beam per unit area for the spot diameter
is the same as power of the laser beam or the electron beam for the
lattice region.
8. The method for producing a three-dimensional shaped product
according to claim 1, further comprising the step of shaping
scanning in the lattice region along the one side direction and the
another side direction is one of: a straight linear form, a
continuous wavy form with regular variation of a curve or segment,
or a shape in which the straight line and the wavy form are
joined.
9. The method for producing a three-dimensional shaped product
according to claim 1, further comprising the step of, based on
straight lines connecting both ends of each of the lines where
scanning is carried out in the lattice region along the one side
direction and the another side direction, setting the mutually
crossing angle to be in a range between 45.degree. to
90.degree..
10. The method for producing a three-dimensional shaped product
according to claim 1, further comprising the step of, based on
straight lines connecting both ends of each of the lines where
scanning is carried out in the lattice region along the one side
direction and the another side direction, setting the sliding
direction of the squeegee to be identical to either the one side
direction or the another side direction.
11. The method for producing a three-dimensional shaped product
according to claim 1, further comprising the step of, based on
straight lines connecting both ends of each of the lines where
scanning is carried out in the lattice region along the one side
direction and the another side direction, setting the sliding
direction of the squeegee to be diagonal with both the one side
direction and the another side direction.
12. The method for producing a three-dimensional shaped product
according to claim 1, further comprising the steps of: sandwiching
powder of the powder layer by mutually adjacent sintered layers
molded by sintering with scanning in the lattice region along the
one side direction and when the powder dispersed by sliding of the
squeegee in the direction crossing a scanning direction is not
sufficient for molding of the powder layer, then newly dispersing
powder with sliding of the squeegee along that direction to
supplement deficient powder at an earlier stage than sintering by
scanning in the scanning direction on the another side.
13. The method for producing a three-dimensional shaped product
according to claim 1, further comprising the step of, as a number
of the sintered layers is increased, the spot diameter of the laser
beam or the electron beam scanning in the lattice region is
sequentially increased, and either the power of the laser beam or
the electron beam is sequentially increased or the speed of
scanning of the laser beam or the electron beam is sequentially
decreased, or both, setting a sequentially decreasing size for open
pores.
14. The method for producing a three-dimensional shaped product
according to claim 1, further comprising the step of, as the number
of the sintered layers is increased, sequentially and gradually
decreasing the interval of the laser beam or the electron beam
scanning in the lattice region and having the predetermined spot
diameter to set a sequentially and gradually decreasing size for
open pores with a step-by-step state.
15. The method for producing a three-dimensional shaped product
according to claim 1, further comprising the steps of: surrounding
the lattice region to be molded by sintering with scanning of the
laser beam or the electron beam in the lattice region along the one
side direction and the another side direction by a gap on an inner
side, and sequentially decreased a size of the gap as layering
progresses, so that molding of the lattice region is carried out in
a tapered form toward the inner side.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method for producing a
three-dimensional shaped product, targeting a surrounding outer
frame and a lattice structure on an inner side after having
established layering based on sequential repetition of a step of
molding a powder layer by dispersion of powder while sliding a
squeegee and sintering the powder layer using a laser beam or an
electron beam, as well as to a three-dimensional shaped product
obtained by the method.
BACKGROUND ART
[0002] Methods for producing three-dimensional shaped products are
known wherein layering is established based on sequential
repetition of a step of molding a powder layer by dispersion of
powder while sliding a squeegee and sintering the powder layer
using a laser beam or an electron beam.
[0003] For many three-dimensional shaped products formed by such
methods for producing the three-dimensional shaped products, the
interior of the shaped product must often have gas permeability,
i.e. a degassing structure, such as in the case of cavity-type die
products or filter products, to allow production of lightweight
three-dimensional shaped products with low density.
[0004] As one three-dimensional shaped product production method
that requires the gas permeability, Patent Document 1, for example,
describes creating gas channels by way of a vesicular structure, in
other words, a porous structure, but strength of the resulting
shaped product is low, because the gas channels composed of the
porous structure are formed by lowering the density of a solidified
material, and the channels through which gas circulates are
undefined and non-linear, therefore making it impossible to avoid
the disadvantage of a low gas flow rate.
[0005] On the other hand, in Patent Document 2, a method for
producing a lattice region is provided wherein, after scanning a
specific metal powder layer with a laser beam having a
predetermined spot diameter in lines several times at predetermined
intervals (:sintering with a first raster configuration), an
adjacent metal powder layer on the upper side is sintered with the
same laser beam in the direction perpendicular to the direction of
the lines (:sintering with second raster configuration), repeating
layering of each metal powder and scanning by the laser beam in
perpendicular directions described above (see Claim 3 and FIG.
4).
[0006] Specifically, according to the invention of Patent Document
2, sintering along the horizontal direction (:X-direction) and
vertical direction (:Y-direction) in which open pores in the
lattice region are formed is carried out alternately every two
layers.
[0007] Referring to FIG. 2 of Patent Document 2, and as shown in
FIG. 10(a), either the vertical or the horizontal direction in
which the laser beam scans matches a sliding direction of the
squeegee, such matching is established based on common technical
knowledge for efficient use of space for production of the
three-dimensional shaped product.
[0008] However, even though the squeegee slides with a
predetermined pressing force to flatten the surface of the metal
powder layer, when the squeegee slides over a line-shaped sintered
layer by scanning of the laser beam in the direction that is
perpendicular to the sliding direction among the vertical and the
horizontal directions during an early stage of molding the powder
layer while sliding, presence of thickness of a pressed metal
powder layer between a site over the line-shaped sintered layer and
a site where another metal powder layer is further superimposed on
the metal powder layer sandwiched between the regions, necessarily
creates a difference in degree of compression undergone by the
pressing force of a tip on a squeegee sliding direction side, even
if width of the squeegee in the sliding direction is larger than a
width of the sintered layer.
[0009] When the laser beam has been scanned in the direction
perpendicular to the line-shaped sintering after sliding of the
squeegee, the aforementioned difference unavoidably results in
molding of an uneven sintered layer with fine irregularities in a
transverse direction, as shown in FIG. 10(b) (note that the
irregular form is exaggerated in FIG. 10(b) for emphasis).
[0010] Further, with alternate sintering every two layers as
according to the invention of Patent Document 2, bonding only takes
place along a two-dimensional surface where the horizontal
direction (:x direction) and the vertical direction (:y direction)
are in contact in the transverse direction, the bonding via a
three-dimensional cube shaped by the horizontal direction (:x
direction) and the vertical direction (:y direction) at identical
heights is non-uniform, and a strength of the lattice region is by
no means sufficient.
[0011] Moreover, in the invention of Patent Document 2 where an
outer frame region is shown in the drawing, no explanation is given
regarding a relationship between sintering in the lattice region
and sintering in the outer frame region.
PRIOR ART DOCUMENTS
Patent Documents
[0012] Patent Document 1: Japanese Patented Official Gazette No.
5776004
[0013] Patent Document 2: Japanese Patented Official Gazette No.
6532180
SUMMARY OF INVENTION
Technical Problem
[0014] It is an object of the present invention to provide a method
for producing a three-dimensional shaped product targeting a
lattice region with a uniform shape and firm bonding, and an outer
frame region disposed on the outer sides of the region, as well as
a structure of a three-dimensional shaped product structure
obtained by the method.
Solution to Problem
[0015] In order to achieve the object stated above, the basic
construction of the present invention is as follows:
[0016] (1) A method for producing a three-dimensional shaped
product in which layering is established based on sequential
repetition of steps of molding a powder layer by dispersion of
powder while sliding a squeegee and sintering the powder layer
using a laser beam or an electron beam, wherein the sintering for
each powder layer is targeted to an outer frame region which is
connected to a gas-permeable lattice region and to the outsides of
the region and is disposed around the entire periphery of the
region, and for each of the powder layers targeted for the lattice
region, a sintered layer is molded along one side direction by
parallel scanning of the laser beam or the electron beam having a
predetermined spot diameter several times in one side direction at
a predetermined interval with the mutually facing outer frame
regions bonded, after which a sintered layer is molded in the other
side direction again by parallel scanning of the laser beam or the
electron beam having the predetermined spot diameter several times
at the predetermined interval with the mutually facing outer frame
regions bonded, in the other side direction that crosses with the
one side direction within each of the same powder layers, the
sintered layer along the one side direction and the sintered layer
along the other side direction are crossing, and the sintered layer
along the one side and the sintered layer along the other side is
bonded in a superimposed state in a crossed region, whereas
sintering is carried out on only one side or only on the other side
in a non-crossed region, while in the outer frame regions, a
continuous sintered layer is molded by scanning the laser beam or
the electron beam having the predetermined spot diameter over the
entire periphery that is surrounded by an inner line and an outer
line;
[0017] (2) The method for producing a three-dimensional shaped
product according to (1) above, wherein for the shape of the outer
frame region, the inner line and the outer line have identical
center locations, and either a regular polygonal shape or a curved
shape in a mutually similar relationship is employed;
[0018] (3) The method for producing a three-dimensional shaped
product according to (1) above, wherein the outer frame regions are
separated by a predetermined width and divided by parallel lines
selected in specific directions, and the laser beam or the electron
beam is scanned in the direction perpendicular to the parallel
direction in an early stage, a later stage, or an intermediate
stage of molding for the sintered layers in the lattice region.
Advantageous Effects of Invention
[0019] In the three-dimensional shaped product according to the
basic construction (1), the basic construction (2) and the basic
construction (3), even if either the one side direction or the
other side direction in which the laser beam or the electron beam
(hereunder referred to as "beam") is scanned is perpendicular to a
sliding direction of the squeegee, since the squeegee slides over a
line-shaped sintered layer molded in a direction crossing that
direction, if a beam scanning direction and the sliding direction
of the squeegee are perpendicular as in the invention of Patent
Document 2, then it is possible to avoid molding for the sintered
layer with fine irregularities in a transverse direction due to
uneven pressing force by sliding of the squeegee as shown in FIG.
10(b), which is caused by differences in thickness of the metal
powder layer.
[0020] Further, in the case of the basic construction (1), for each
powder layer, the bonding is three-dimensional in a range with
identical height where a line-shaped sintered layer formed by
scanning of the beam in one side direction and a line-shaped
sintered layer formed by scanning of the beam on the other side are
formed by the same powder layer, so that the sintered layer along
the one side direction and the sintered layer along the other side
direction are crossing, the sintered layer along the one side and
the sintered layer along the other side is bonded in the
superimposed state in the crossed region and the sintering is
carried out on only one side or only on the other side in the
non-crossed region, with three-dimensional cuboid bonding which is
clearly stronger than bonding along two-dimensional sides that are
in mutual contact in the transverse direction as according to the
invention of Patent Document 2, thus allowing the lattice region to
be ensured by firm bonding.
[0021] In the basic construction (1), sintering in the lattice
region and sintering in the outer frame region can be sequentially
carried out efficiently for each powder layer.
BRIEF DESCRIPTION OF DRAWINGS
[0022] FIG. 1 shows a method for producing the basic construction
(1) in which a shape of sintered layers by scanning a beam along
one side direction and the other side direction is straight linear,
where (a) is a plan view of an embodiment in which both directions
are perpendicular, (b) is a plan view of an embodiment in which
both directions are mutually diagonal, and (c) is a cross-sectional
view of sequentially molding from a first layer to a second layer,
in a beam scanning direction that connects A-A in (a) and (b).
[0023] FIG. 2 shows a method for producing the basic construction
(1) in which the shape of the sintered layers by scanning the beam
along one side direction and the other side direction is wavy,
where (a) is a plan view of an embodiment in which both directions
of a wavy form with a regular varying curve are perpendicular, (b)
is a plan view of an embodiment in which both directions of the
wavy form with a regular varying segment are mutually diagonal, and
(c) is a cross-sectional view of sequentially molding from the
first layer to the second layer, in the beam scanning direction
that connects A-A in (a) and (b).
[0024] FIG. 3 shows an embodiment of the basic construction (2),
where (a) is a plan view of a square as a typical example of a
regular polygonal shape, and (b) is a plan view of a circle as a
typical example of a curved shape.
[0025] FIG. 4(a) shows an embodiment of the basic construction (3),
as a plan view showing a case where the parallel lines are the
directions of specific sides of the square, when the square shape
of FIG. 3(a) is employed (the double arrows indicate the directions
perpendicular to the parallel directions).
[0026] FIG. 4(b) shows an embodiment of the basic construction (3),
as a plan view showing a case where the parallel lines are in
directions that form a maximum distance in the regions surrounded
by the inner line and outer line forming regular polygonal shapes
or curved shapes, given a predetermined width, when the square
shape of FIG. 3(a) is employed (the double arrows indicate the
directions perpendicular to the parallel directions).
[0027] FIG. 4(c) shows an embodiment different from the basic
construction (3) for sintering in the outer frame region, as a plan
view showing scanning of the beam along a trajectory where the
inner line and the outer line are in a similar relationship, when
the circle of FIG. 3(b) is employed (the curved single direction
arrows indicate the beam scanning direction).
[0028] FIG. 5 is a plan view showing a relationship between the
beam scanning direction and the sliding direction of the squeegee,
where (a) shows an embodiment in which either the one side
direction or the other side direction is perpendicular, and (b)
shows an embodiment in which both directions are mutually
diagonal.
[0029] Note that the outline arrows indicate the direction of
sliding of the squeegee while it disperses powder.
[0030] FIG. 6 shows an embodiment in which insufficient metal
powder has been supplemented when the powder between sintered
regions has been deficient at the stage of beam scanning in one
side direction, where (a) shows a state in which the powder
dispersed by sliding of the squeegee in the direction crossing the
scanning direction on one side is insufficient for molding of the
powder layer, (b) shows a state in which the powder that was
deficient by further scanning of the squeegee has been
supplemented, and (c) shows a state in which the beam has been
scanned in the other side direction. Note that the outer frame
regions are omitted in (a), (b) and (c).
[0031] FIG. 7 shows an embodiment in which size at open pores is
sequentially decreased while layering by varying beam spot diameter
and beam power or scanning speed, where (a) is a plan view showing
a sequentially increasing shaped width and (b) is a cross-sectional
view in the transverse direction.
[0032] FIG. 8 shows an embodiment in which, after having selected
the beam having a predetermined spot diameter, the interval of the
beam scanning parallel to the one side direction and the other side
direction is set to sequentially and gradually decrease, to
sequentially and gradually reduce the size of the open pore, where
(a) is a plan view showing sequential and gradual decrease in a
beam interval, and (b) is a cross-sectional view in the transverse
direction showing the same condition as (a) (the dotted lines
indicate the state where the early stage beam that is varied and
the later stage beam that is varied are mutually superimposed, for
the beam scanning in the other side direction in the region where
the beam interval gradually decreases with a step-by-step
state).
[0033] FIG. 9 is a cross-sectional view in the transverse direction
showing a configuration for an example in which a partial region
surrounded by the lattice region is tapered.
[0034] FIG. 10 shows the construction of the invention of Patent
Document 2, where (a) is a plan view at the stage where the
squeegee is sliding, and (b) is a cross-sectional view in the
transverse direction at the same stage. Note that the outline
arrows indicate the direction of sliding of the squeegee while it
disperses the powder.
DESCRIPTION OF EMBODIMENTS
[0035] When using a die that is a three-dimensional shaped product
with an outer frame and an inner lattice structure obtained by the
basic constructions (1), (2) and (3), powder used is usually metal
powder.
[0036] However, when the three-dimensional shaped product is a
product other than the die such as a filter, the powder does not
necessarily need to be the metal powder, and plastic powder, etc.
are also typically used, and such a state is identical in the case
of the three-dimensional shaped product has a low density.
[0037] Upon appropriate selection of such a material, the basic
construction (1), as shown in FIG. 1(a), (b) and (c) and FIG. 2(a),
(b) and (c), is a method for producing the three-dimensional shaped
product in which layering is established based on sequential
repetition of steps of molding a powder layer 3 by dispersion of
powder while sliding a squeegee 6 and sintering the powder layer 3
using a laser beam or an electron beam, wherein the sintering for
each powder layer 3 is targeted to an outer frame region 2 which is
connected to a gas-permeable lattice region 1 and to the outsides
of the region 1 and is disposed around the entire periphery of the
region 1, and for each of the powder layers 3 targeted for the
lattice region 1, a sintered layer 41 is molded along one side
direction by parallel scanning of the laser beam or the electron
beam having a predetermined spot diameter several times in one side
direction at a predetermined interval with the mutually facing
outer frame regions 2 bonded, after which a sintered layer 42 is
molded in the other side direction again by parallel scanning of
the laser beam or the electron beam having the predetermined spot
diameter several times at the predetermined interval with the
mutually facing outer frame regions 2 bonded, in the other side
direction that crosses with the one side direction within each of
the same powder layers 3, the sintered layer 41 along the one side
direction and the sintered layer 42 along the other side direction
are crossing, and the sintered layer 41 along the one side and the
sintered layer 42 along the other side is bonded in a superimposed
state in a crossed region, whereas sintering is carried out on only
one side or only on the other side in a non-crossed region, while
in the outer frame regions 2, a continuous sintered layer 43 is
molded by scanning the laser beam or the electron beam having the
predetermined spot diameter over the entire periphery that is
surrounded by an inner line and an outer line.
[0038] For the basic construction (1), the layering and the
sintering are carried out in the lattice region 1 and the outer
frame region 2 in each layer, and the outer frame region 2 is
surrounded by the inner line and the outer line, and has the width
formed by both lines.
[0039] Various embodiments may be employed for the shape of the
outer frame region 2 formed by the inner line and the outer line, a
typical example of the basic construction (2) is composed in that
the inner line and the outer line have identical center locations,
and either a regular polygonal shape or curved shape in a mutually
similar relationship is employed, and the square shown in FIG. 3(a)
and the circular shape shown in FIG. 3(b) are embodiments of the
simplest shapes.
[0040] Polygonal shapes may be hexagonal, rectangular or square
shapes while curved shapes may be ellipsoid or circular shapes.
[0041] For the basic construction (2), the outer frame region 2 can
be formed with a uniform structure by the inner line and the outer
line having similar shapes.
[0042] For sintering of the outer frame region 2, it is sufficient
to form the continuous sintered layer 43 in the region surrounded
by the inner line and the outer line as in the basic construction
(1), the continuous sintered layer 43 is generally created in a
manner unrelated to formation of the sintered layers 41, 42 in the
lattice region 1.
[0043] In most cases, however, the basic construction (3) will be
employed in which the outer frame regions 2 are separated by a
predetermined width and divided by parallel lines selected in
specific directions, and the laser beam or the electron beam is
scanned in the direction perpendicular to the parallel direction in
an early stage, a later stage, or an intermediate stage of molding
for the sintered layers 41, 42 in the lattice region 1.
[0044] In the case of the basic construction (3), computer
processing is facilitated wherein division is performed along the
parallel lines separated by the predetermined width, and more
simple control can be maintained by specifying a beam scanning
direction.
[0045] In the basic construction (3), sintering of the outer frame
regions 2 is usually selected to be in the early stage or the later
stage of the sintering of the lattice region 1, although the
intermediate stage may also be selected.
[0046] In almost all cases, the intermediate stage is selected to
be the early stage of carrying out the sintering in the other side
direction after completion of the sintering in the one side
direction.
[0047] This is because shaping of the sintered layer 41 in the one
side direction and the sintered layer 42 in the other side
direction must be carried out continuously.
[0048] For the basic construction (3), when the regular polygonal
shape is selected as the basic construction (2) and the direction
of a specific side of the regular polygonal shape is selected for
the parallel line direction, it is possible to carry out simple
scanning in which the specific side is completely sintered by
scanning of the beam in the direction perpendicular to the parallel
direction, while the other sides are completely sintered by
scanning of the beam within a divided region, as shown in FIG.
4(a).
[0049] In the basic construction (3), after selecting the regular
polygonal shape or the curved shape for the basic construction (2),
when a direction has been selected for parallel lines as the
direction that forms a maximum distance in the region surrounded by
the inner line and the outer line forming the regular polygonal
shape or the curved shape of the basic construction (2), for the
predetermined width, as shown in FIG. 4(b), and scanning location
has been slid sequentially from the end of one of the parallel
lines reaching to the end of another parallel line, the scanning
width is sequentially increased in stages from the initial to reach
a maximum at the intermediate stage and thereafter sequentially
decreases to 0, thus allowing relatively simple control of a beam
scanning width.
[0050] When the regular polygonal shape is square, the direction of
the parallel lines that exhibits the maximum width is necessarily a
direction of 45.degree. with respect to the parallel sides, so long
as it is formed at an apex where the inner line and the outer line
are adjacent.
[0051] Separately from sintering by the basic construction (3), it
is possible to employ a sintering method by scanning of the beam
along a trajectory such that the inner line and the outer line
forming the regular polygonal shape or the curved shape of the
basic construction (2) are in a similar relationship at the early
stage, the later stage or the intermediate stage of molding for the
sintered layers 41, 42 in the lattice region 1, as shown in FIG.
4(c).
[0052] With a sintering method in which movement is along
trajectory lines in this similar relationship, a trajectory pattern
is set in advance along the similar shape and the size of the
pattern is sequentially varied as it recedes from the center
location, which allows simple control to be effected.
[0053] In a sintering method with this trajectory as well, it is
most common to select the early stage or the later stage of
sintering of the lattice region 1, but even if the intermediate
stage is selected, the early stage in which sintering is complete
in the one side direction and sintering is begun in the other side
direction is selected in almost all cases, as for the basic
construction (3).
[0054] Although it is possible to select a method in which a spot
diameter larger than the spot diameter for the lattice region 1 is
used for sintering with the beam in the outer frame region 2, and a
greater number of scans is also set, a large beam diameter is more
efficiently suitable for sintering.
[0055] For the laser beam or the electron beam that scans the outer
frame region 2, in particular, if an embodiment is employed in
which a spot diameter is selected that is larger than the spot
diameter in the lattice region 1, and power density is set so that
the power of the beam per unit area for the spot diameter is the
same as the power of the beam in the lattice region 1, then it will
be possible to obtain a sintered state with firm bonding the same
as the lattice region 1 in the outer frame region 2 as well.
[0056] The spot diameter of the beam in the basic construction (1)
is usually selected within a range of 0.05 mmcp to 0.6 mmcp, while
in most cases the predetermined interval is selected to be 0.06 mm
to 1.0 mm and the width of an open pore 11 is set to be in the
range of 0.01 mm to 0.4 mm.
[0057] In the case of the basic construction (1), the shapes of the
lines formed by parallel scanning in the lattice region 1 along the
one side direction or the other side direction for each of the same
powder layers 3 may be selected from among various shapes. FIG.
1(a) and (b) show rectilinear forms, FIG. 2(a) shows an embodiment
with a continuous wavy form with a regularly varying curve (FIG.
2(a) is a case of a continuous circular arc shape with a
sequentially and alternately varying curved direction), and FIG.
2(b) shows an embodiment with a continuous wavy form with a
regularly varying segment (FIG. 2(b) is a case of a continuous form
with the segment direction sequentially and alternately regularly
varying by approximately 45.degree.), and naturally the shapes
formed by bonding of the wavy and rectilinear forms may also be
employed.
[0058] Simple scanning is possible with the rectilinear form, while
sintered density per unit area of a plane can be increased in the
beam scanning direction with the wavy form, compared to the
rectilinear form.
[0059] As shown in FIG. 1(a) and FIG. 2(a), angles in both
directions, based on straight lines connecting both ends of each of
the lines of the sintered layer 41 in the one side direction and a
straight line connecting both ends of each of the lines of the
sintered layer 42 in the other side direction in the lattice region
1, are typically right angles, but slanted directions may also be
selected as shown in FIG. 1(b) and FIG. 2(b).
[0060] However, considering that sintering is most efficient with a
perpendicular relationship, even for the slanted direction, it is
most common to set an angle of 45.degree. or greater, and therefore
an intersection angle between the one side direction and the other
side direction will still usually be selected as an angle between
45.degree. and 90.degree. for the basic construction (1).
[0061] Note that the one side direction or the other side direction
is selected for scanning of the beam in the outer frame region 2,
but for the outer side of the outer frame region 2, usually molding
is parallel to the outer side of the lattice region 1 as shown in
FIG. 1(a) and (b) and FIG. 2(a) and (b).
[0062] In consideration of efficient use of space, when comparing
both sintering directions, with the sintered layer 41 in the one
side direction or the sintered layer 42 in the other side direction
for the sliding direction of the squeegee 6 and scanning of the
beam, as shown in FIG. 5(a), they not only match the sliding
direction, but they are also in the perpendicular relationship.
[0063] In this state, even if the sintered layer 42 is present in
the perpendicular direction as shown in FIG. 5(a), so long as the
squeegee 6 slides above the sintered layer 41 in the matching
direction, it is possible to avoid unevenness on the surface of the
powder layer 3 as shown in FIG. 10(a) and (b) described above for
the invention of Patent Document 2.
[0064] For the embodiment shown in FIG. 5(a), however, thickness of
the powder layer 3 further molded as the squeegee 6 slides differs
in the region where the line-shaped sintered layer 42 is present
below and perpendicular to the sliding direction, and in the region
sandwiched by the line-shaped sintered layer 42. And as a result,
some difference necessarily arises in the effect of pressing force
from the sliding direction edge of the squeegee 6.
[0065] Specifically, on the lower side, the region where the
line-shaped sintered layer 42 is not present has a greater effect
due to pressing force by the tip of a traveling direction of the
squeegee 6 than the region where the line-shaped sintered layer 42
is present, and consequently it is converted to a somewhat indented
state, though the degree is much lower than in FIG. 10(b), often
resulting in a fine irregular shape being formed alternately along
the sliding direction of the squeegee 6.
[0066] In contrast, in the case of the embodiment where the
reference is based on the straight lines connecting both ends where
scanning is carried out in the lattice region 1 along the sintered
layer 41 in the one side direction and the sintered layer 42 in the
other side direction as shown in FIG. 5(b), and the direction of
sliding of the squeegee 6 in the one side direction and the other
side direction are diagonal, the line-shaped sintered layer 42 is
not present in the lattice region 1 along the direction
perpendicular to the sliding direction of the squeegee 6 as shown
in FIG. 5(a), and therefore creation of irregularities in the
powder layer 3 along the sliding direction of the squeegee 6 can be
avoided, and the lattice region 1 can be molded in a more stable
condition based on molding of a uniform powder layer 3.
[0067] Since the region where the sintered layer 41 of the beam in
the one side direction and the sintered layer 42 of the beam in the
other side direction are superimposed is extremely narrow, and
there is no difference in the effect of this region and the region
where sintering is carried out only on the one side or only on the
other side on sliding of the squeegee 6, the presence of the
sintered layers 41 and 42 by superimposing does not take away the
merits of the embodiment shown in FIG. 5(b).
[0068] When sintering with the beam in the one side direction has
been carried out for the basic construction (1), a portion migrates
to the sintered layer 41 side, and as a result, each region
surrounded by the sintered layer 41 on both sides sometimes has a
deficiency of the powder dispersed by sliding of the squeegee 6 in
the direction crossing the scanning direction compared to the
amount necessary for molding of the powder layer 3 as shown in FIG.
6(a), with the state of deficiency tending to be greater with a
wider width of the region sandwiched by the line-shaped sintered
layer 41.
[0069] When sintering is immediately carried out by scanning of the
beam in the other side direction despite this state of deficiency,
the line-shaped sintered layer 42 molded by the other side scanning
becomes uneven, making it impossible to avoid molding of an uneven
lattice region 1.
[0070] In order to avoid such a situation, when the powder of the
powder layer 3 sandwiched by adjacent sintered layers is
insufficient after sintering by scanning in the lattice region 1
along the one side direction as shown in FIG. 6(b) for the basic
construction (1), it is possible to employ an embodiment in which a
deficient powder is supplemented by renewed dispersion of powder
with sliding of the squeegee 6 along that direction, at a stage
prior to sintering by scanning in the scanning direction on the
other side.
[0071] According to this embodiment, as shown in FIG. 6(c), a
uniform sintered layer 42 can be formed during sintering of the
next beam on the other side.
[0072] The open pores 11 formed in the basic construction (1) are
surrounded on all sides by the sintered layers 41, 42, by molding
on both the sintered layer 41 on the one side direction and the
sintered layer 42 on the other side direction.
[0073] However, the widths of the lines for molding for the
sintered layers 41, 42 do not necessarily have to have the same
widths.
[0074] That is, as shown in FIG. 7(a) and (b), an embodiment may be
employed in which, as a number of the sintered layers is increased,
the spot diameter of the beam in the lattice region 1 is
sequentially increased, and either the powder of the beam is
sequentially increased or the speed of scanning of the beam is
sequentially decreased, or both, to set a sequentially decreasing
size for the open pores 11.
[0075] In addition, as shown in FIG. 8(a) and (b), an embodiment
may be employed in which, as the number of the sintered layers is
increased, the interval of the laser beam or the electron beam
scanning in the lattice region and having the predetermined spot
diameter is sequentially and gradually decreased to set a
sequentially and gradually decreasing size for the open pores 11
with a step-by-step state.
[0076] When a cavity die is produced by one of the aforementioned
embodiments, the area of an outlet where gas stream is ejected is
made smaller than an inlet where the gas stream is infused, thereby
allowing ejection of the gas stream for molding at necessary
pressure.
[0077] A working example of the invention will now be
described.
EXAMPLE
[0078] For molding in the lattice region 1, tubing for degassing is
often situated below, which results in a base plate 5 being set
only below the region where molding of the outer frame region 2 is
expected to take place, as shown in FIG. 9, and molding of the
lattice region 1 is often carried out without setting the base
plate 5 below the region where molding of the lattice region 1 is
expected to take place.
[0079] In such cases, it is essential for molding of the lattice
region 1 to be carried out sequentially inward from the surrounding
outer frame region 2.
[0080] For Example 1, the lattice region 1 to be molded by
sintering with scanning of the beam in the lattice region 1 along
the one side direction and the other side direction is surrounded
by a gap on an inner side, as shown in FIG. 9, with the size of the
gap being sequentially decreased as layering progresses, so that
molding of the lattice region 1 is carried out in a tapered form
toward the inner side.
[0081] Employing such a tapered form allows the lattice region 1 to
have the necessary width in the transverse direction, and also a
predetermined strength.
INDUSTRIAL APPLICABILITY
[0082] The present invention is revolutionary in that it allows a
lattice structure to be obtained with firm bonding and a uniform
shape, and it widens potential range of use of three-dimensional
shaping with a lattice structure.
REFERENCE SIGNS LIST
[0083] 1: Lattice region [0084] 11: Open pore [0085] 12: Tapered
region [0086] 2: Outer frame region [0087] 3: Powder layer [0088]
41: Sintered layer in one side direction [0089] 42: Sintered layer
in the other side direction [0090] 43: Continuous sintered layer
[0091] 5: Base plate [0092] 6: Squeegee
* * * * *